Formation chip sampling apparatus

ABSTRACT

Formation chip sampling method and apparatus for separating solids from the liquid contained in drilling mud which has been obtained from an earth boring operation. The returned drilling mud is flow connected in series relationship to a gas separator, a splitter which reduces the amount of sample to be treated, and to a reservoir. A pump flow connects the reservoir to a cyclone type separator which removes the solids from the sample. The reservoir further includes a level controller which provides make-up liquid so as to provide the pump with optimum suction conditions.

United States Patent 51 May 23, 1972 Elenburg [54] FORMATION CHIPSAMPLING APPARATUS [72] Inventor: Wayland D. Elenburg, Box 1588,

Monahans, Tex. 79656 [22] Filed: Jan. 21, 1970 [21] Appl. No.: 4,546

[52] US. Cl ..175/206, 175/66, 175/217 [51] Int. Cl ..E2lb 21/00 [58]Field of Search 175/66, 69, 205-207, 175/209, 217

[56] References Cited UNITED STATES PATENTS 2,786,652 3/1957 Wells..175/206 X 2,852,091 9/1958 Boudreaux et al... ....175/206 X 2,870,9901/1959 Bergey ..175/217 X 2,886,287 5/1959 Croley ..175/206 2,919,8981/1960 Marwil et al.. ..175/66 2,923,151 2/1960 Engle et a1. 175/206 X2,941,783 6/1960 Stinson ..175/206 Primary Examiner-David H. BrownAttomey-Marcus L. Bates ABSIRACT llClahm,8D|-awingligures PATENTEB MAY 23 1972 sum 1 or 3 FIG. I

INVBNTOR WAYLAND D. ELENBURG MARCUS L. BATES PATENTEDMY 2 3 m2 F'LF'EEI2 OF 3 FIG. 3

FIG. 4

FIG. 5

INVENTOR WAYLAND D. ELENBURG MARCUS L. BATES PATENTEDMAY 23 I972 TAMI 3BF 3 BOREHOLE FIG. 8

[NV/5N )R, WAYLAND 0. ELENBU BY MARCUS L. BATES FORMATION CHIP SAMPLINGAPPARATUS BACKGROUND OF THE INVENTION In the chip drilling process, dualconcentrically arranged drill pipe are connected between a drill bit anda swivel with drilling fluid flowing to and from the bit incounter-current relationship in order to cool and lubricate the drillpipe and bit, and to remove chips and other cuttings from the bottom ofthe borehole by circulating the cuttings to the surface of the groundwhere the cuttings may be subsequently studied by geologists in order todetermine the physical and chemical properties of the strata of theearth through which the borehole has been formed. At the bottom of theborehole the drilling fluid picks up or entrains the chips and cuttingsand transports them upwardly within the central pipe, or altematively,within the annulus formed by the drill pipe, where the cuttings flow tothe surface of the earth, all of which is known to those skilled in theart; as evidenced by Elenburg, US. Pat. No. 3,439,757; to whichreference is made for further background of the invention.

Retrieving representative core samples, reducing the core samples to aconvenient size which is conductive to study thereof, and relating thesamples to the specific depth of the borehole from which they originatedis extremely important in order for the geologist to carry out properanalysis of the various strata encountered.

Heretofore it has been customary for others to flow connect the entiredrilling mud flow stream from the borehole to a flow divider apparatuswhich separates the major flow stream into several flow paths so as togreatly reduce the volumeof the drilling mud or chip bearing flow streamwhich is to be treated for subsequent analysis. Often the flow isimproperly divided due to the physical characteristics of the solids andthe mechanics of the flow divider, all of which results in inaccurateanalysis of the borehole for the reason that one divided flow streamdiffers in composition or mixture from another divided flow stream.After the mud sample has been reduced in volume by selecting one of theflow streams for analysis, it is necessary to permit the solids tosettle by gravity, after which the clarified water is siphoned off ordecanted, and the remaining saturated solids or residue heated toevaporate the liquid therefrom.

It is therefore desirable to be able to split a stream of drilling mudcontaining samples from the chip drilling process into any desiredfraction of the main flow stream wherein the smaller fraction of themain flow is identical in composition or mixture to the remainder of theflow. It is also desirable to be.

able to treat this fraction of flow in an improved manner which removesthe solids therefrom, and to be able to relate the retrieved solidsamples to the particular depth of the borehole from which the sampleoriginated.

SUMMARY OF THE INVENTION This invention relates to formation chipsampling apparatus and method for separating solids from drilling mudwhich may be obtained from an earth boring operation so as to enablesubsequent analysis thereof. As the drilling mud flows from theborehole, it exits at the swivel and flows to a separator where the airis removed therefrom. From the separator the flow continues to asplitter where a fraction of the flow is separated from the main flow.The fractional flow continues to a reservoir with the reservoir havingfluid level control means associated therewith for supplying makeupwater thereto in order to always maintain a fluid level therein. Thecontents of the reservoir is pumped under a positive pressure to acyclone separator. The pump flow and the physical dimensions of thecyclone separator are sized with respect to one another so as to providean optimum separation of solids from the liquid at the cycloneseparator. Where deemed desirable, and especially when utilizing thechip drilling process, a screen may be interposed between the splittermeans and the reservoir so as to reduce the load on the pump while atthe same time maintaining large chips in an undamaged condition whichwill enhance the subsequent analysis thereof. The screened solids arecombined with the solids removed from the cyclone separator and placedin a suitable container for storage or shipment.

It is therefore a primary object of this invention to provide a methodof obtaining formation chip samples by separating solids from drillingmud.

Another object of the present invention is the provision of a method ofobtaining a fraction of the flow obtained from a borehole formingoperation which is representative of the main flow; and of separatingthe solids from the liquid contained in the fractional flow.

A still further object of the present invention is the provision ofapparatus which obtains formation chip samples from a chip drillingoperation by separating solids from the drilling mud.

A still further object of the present invention is the provision offormation chip sampling apparatus which removes air from drilling mud,separates the drilling mud flow stream into a fractional part whereinthe fractional part contains solids which are representative of thesolids contained within the main flow stream, and which separates thesolids from the liquid of the fractional component of the main stream.

Still another object of the present invention is a method of removingsolids from drilling mud so as to provide a formation chip sample whichcan be related to the particular depth of borehole from which the sampleoriginated.

The above objects are attained in accordance with the present inventionby the provision of method and apparatus for obtaining formation chipsamples as set forth in the above abstract and summary.

Various other objects and advantages of this invention will becomereadily apparent to those skilled in the art upon reading the followingdetailed description and by referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAVVINGS FIG. 1 is a part diagrammatical, partschematical representation in the form of a flow sheet which describesthe essence of the method of the present invention;

FIG. 2 is a side elevational view of apparatus previously seen in FIG.1;

FIG. 3 is a top plan view of the apparatus disclosed in FIG. 2;

FIG. 4 is a top plan view of part of the apparatus seen in FIG. 1, withsome parts thereof being diagrammatically illustrated by dot-clashlines; and

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4, withsome parts thereof being unsectioned for clarity;

FIG. 6 is a part diagrammaticahpart schematical representation in theform of a flow sheet which describes another embodiment of the presentinvention;

FIG. 7 is an enlarged, part cross-sectional view, taken along line 7-7of'FIG. 6; and

FIG. 8 is a reduced top plan view of a part of the apparatus disclosedin FIG. 6, with some parts thereof being broken away therefrom in orderto better disclose the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in thediagrammatical representation of FIG. I, the present invention is usedin conjunction with a borehole forming operation, broadly indicated bythe arrow at numeral 10, wherein there is seen concentrically arrangeddrill pipe extending into the ground with the upper terminal end thereofbeing connected to a swivel 12. Drilling fluid, or drilling mud, ispumped to the swivel in the usual manner while drilling fluid containingchips and particles of the formation being penetrated are retrieved atgooseneck 16. The gooseneck is flow connected to tangential inlet 17 ofair separator means I 18. The air separator has an upwardlydepending-centrally located conduit 19 from which air escapes.Theair-free liquid flows through bottom outlet and is directed into asplitter means 21.

The splitter includes a large outlet 22 which is flow connected to mudpit 23 by any suitable means, and to which the major portion of the flowis conducted. Small outlet 24 receives the remaining fraction of thedrilling mud which is originally returned from the borehole. Theremaining portion or fraction of the mud flows through screen 25 inorder to remove large particles or chips therefrom. The fraction of thedrilling fluid which includes the smaller cuttings or particles whichwere not retained by the screen continues to flow on to the reservoir at26. The upwardly opening reservoir has a sloped bottom to which a loweroutlet is flow connected to pump means 27.

The pump can be actuated by any suitable means, as for example, agasoline motor. The pump provides a high pressure flow to tangentialinlet 28 of cyclone separator 29. As the drilling fluid flows throughthe cyclone separator, the liquid is separated from the remaining solidscontained therein, with the liquid finally exiting at 30 where it can beflow connected to any suitable disposal means, as for example, the mudpit, while solids fall through lower outlet 31 where they are retrievedwithin any suitable receptacle 32. A source of makeup water (not shown)is connected to valve means 33 which in turn is controllably flowconnected to a journaled float means 34 by the illustrated linkage. Thefloat and valve assembly provides a level controller device forcontrolling the flow of makeup water into the reservoir so as tomaintain a suction for the pump at all times.

FIGS. 2 and 3 show the details of the separator apparatus which includesa gear driven pump 27 having rubber impellers thereon and which iscapable of producing a flow rate and pressure consistent with the designof cyclone separator 29 and to the mud flow rate into the reservoir.

The reservoir is provided with a means for maintaining a fluid leveltherein, preferably in the form of a styrofoam float 34 which has asupport arm depending therefrom and journaled to any convenientstructure, as for example a side wall of the reservoir. The arm isconnected by linkage 33' to the valve means 33 so as to actuate thevalve as the fluid level within the reservoir changes. The valve meanshas an inlet which is flow connected to any suitable source of makeupwater and an outlet into the trough. The valve means can alternativelybe connected to flow directly into the outlet of the reservoir if deemeddesirable.

The pump is driven by an internal combustion gasoline motor of thefollowing described type: Wisconsin Engine, 3 X 3% size. The pump is ofthe followingdescribed type: gear driven, rubber impellers, capable of40 g.p.m. at 9-15 p.s.i.g., manufactured by Booie. The inlet of thecyclone separator is provided with 40 g.p.m., and is available fromKerbs Engineering, 1205 Crysler Drive, Menlo Park, California, ModelD4B-l 2.

Looking now to the details of FIGS. 4 and 5, the before mentioned airseparator 18 is seen to be in the form of a cylindrical tub havingtangental inlet 17 connected to an upper extremity of the sidewallthereof, and with an upwardly depending reduced diameter air outlet 19being provided at the upper end thereof. Outlet 20 is in the form of adownwardly and outwardly directed elbow which is arranged in overhangingrela tionship with respect to the splitter so as to cause the mudflowing therefrom to impinge against the rotating vanes of the splitter,as will be pointed out in greater detail later on.

The splitter has an upwardly opening interior as indicated by the arrowat numeral 35 which is formed by the stator or fixed tub portion 36.Within the stator there is rotatably disposed a rotor comprised ofcylinder 37 having a multiplicity of radially disposed vanes 38 whichrigidly connect the cylinder to a tubular element 39. The tubularelement is rigidly affixed to a shaft 40 with the shaft having spacedapart bearings 41, 42, each of which are located at the upper and lowerextremity of the shaft so as to rotatably support the shaft from thefixed members 43 and 44. Tubular member 39 is received within theupwardly opening complementary fixed tubular member 45. Inwardly slopedfloor members 46, 48 are affixed between adjacent vanes and form spacedapart catch basins between some of the vanes, with the lower extremityof the basins being apertured as seen at 49 so as to communicate theinterior of the complementary fixed tubular member therewith.

A pair of spaced apart rails 51 underlie the trough 24 and provides asupport means for the before mentioned screen so as to enable the screento be conveniently interposed between small outlet 24 and the reservoir.While the particular embodiment disclosed herein illustrates each sixtharea as being a basin, it is preferred that each fourth area betweenadjacent vanes be provided with a lower bulkhead or floor so as toprovide the before mentioned split of 25 percent of the flow.Alternatively, other splits may be achieved by merely varying the numberof floor members employed within the rotor.

In the embodiment set forth in FIGS. 6-8, the numerals used inconjunction therewith refer to similar numerals used in conjunction withFIGS. 1-5, wherever possible. As seen in FIGS. 6-8, mud from thedrilling operation flows through air separator 118, which may beidentical to the air separator of FIGS. l-5. A screen is interposedbetween the air separator liquid outlet 120 and the entrance of hopperor reservoir 126. The upper edge portion of the reservoir forms asupport for the frame of the screen.

Valve 133 is actuated by float level device 134 in a manner similar tothe arrangement of the level controller disclosed in FIGS. 1-5. Outletis connected to a bypass Tee" 161, with the tee having the illustratedvalve therein for flowing mud to the mud pit. Valve 162 connects the teeto pump 127, which in turn is connected to inlet 128 of separator means129.

The separator has a liquid outlet 130 and a solids outlet 131.Receptacle 132 can be any suitable container for receiving core samplesfrom the separator means.

The liquid outlet 130 is freely received within the inlet elbow 163 ofstorage tank 165 with the outer peripheral wall surface of the outletbeing spaced apart from the inner peripheral wall surface of the elbow.Overflow 164 can be flow connected to the mud pit, and is located belowthe inlet of the elbow so as to maintain the liquid height within thetank at a level which always leaves room for liquid flow from theseparator. Outlet 166 is flow connected to the valve 133 of the liquidlevel control means.

OPERATION In operation, drilling mud is circulated from a main mud pump(not shown), to the swivel where it is forced through the drill stringannulus downhole to the drill bit, and back through the centralpassageway to the inlet 17 of the air separator. The formation samplescut by the action of the bit are in the form of chips and cuttings, andare transported by the drilling fluid into the air separator 18. The airseparator can take on several different forms but preferably is similarto a centrifuge in that a vortex is established by the tangental inlet17, thereby causing the drilling fluid to be separated from aircontained therewithin. The air separator is especially useful where thechip drilling process is supplemented with air drilling, but is notconsidered indispensable to the process. As drilling mud exits fromoutlet 20, it impinges against the vertically disposed radiating vanesof the splitter, causing a rotational motion to be imparted into therotor. Since the rotor is spaced apart from the wall of the stator andjournaled at its upper and lower extremity, it will rotate at a r.p.m.or with a peripheral velocity which is dependent upon the flow rate ofthe drilling mud received therewithin. The major portion of the mud flowstream is free to flow through the spaced-apart vanes at 47 and to theoutlet 22, while a smaller fraction thereof is intercepted by the catchbasins formed by the floor members 48.

As the mud flows through the spaced apart vanes 38, that is, theadjacent vanes which have no floor therebetween, it continues on throughthe rotor and into the lower extremity of the tub or stator where itthen flows through outlet 22 and is directed to the mud pit 23. Thesmaller fraction of the drilling fluid which flows into the catch basin,however, is trapped by the floor member and diverted through aperture49, into the rotatable tubular member, and into fixed tubular member 45,where it then flows from lower chamber 50 and through outlet 24.

The number of catch basins 48 may be varied to provide any splitdesired, as for example, one sixty-fourth or one-half of the totalreturned mud flow may be deemed desirable as a feed rate into thereservoir 26. The number of catch basins determine the formation samplesize as well as the load placed on the screen, reservoir, pump, andcyclone.

Trough 24 preferably is arranged in overhanging relationship withrespect to reservoir 26 so as to enable fluid therefrom to flow bygravity thereinto. Screen is preferably of 60 mesh size and isinterposed between trough 24 and the reservoir by merely resting theedge portions of the screen on spaced apart support members 51 asgenerally indicated by the arrow at numeral 25 Since most chip drillingoperations employ a fluid circulation rate of about 140 gallons perminute when making a 4% inch diameter hole, it is evident that thefraction of this amount which will be divided out by the splitter andreceived within the reservoir is dependent upon the ratio of catchbasins to the open vanes. Since the pump 27 preferably receives exactly40 gallons per minute, and assuming a 25 percent split, it is evidentthat the float 34 must open valve 33 a sufficient amount to supply 5gallons of fresh make-up water per minute in order to maintain a fluidlevel within the reservoir.

Pump 27 delivers a constant flow of fluid to the cyclone separator,which can take on several different forms, and preferably is essentiallya vertical cylinder with the usual inlet stream 28 being introducedtangentally near the top so as to give a spinning motion to the liquidtraveling therethrough. The centrifugal force acting on the suspendedsolids tends to throw them radially to the side of the cyclone as thesolids spiral downward to the conical bottom where they are removed at31. The separated liquid is disposed of at the top, with the conduit 30being a conventional outlet. With the cyclone separator operating withinits most efficient range, essentially no liquid is lost through thesolids outlet, and essentially saturated solids drop into the receptacle32. it is for this reason that the pump 27 must always operate withinits most efficient range, or otherwise the operation of the cyclone willnot produce this desired effect.

The cyclone effectively removes all of the suspended solids. in oneseries of test carried out in accordance with the present method, onehalf gallon of 60 mesh sand was introduced into the reservoir, andseparated by the cyclone with five passes through the separator portionof the equipment being made. The accumulated loss of sand during thesefive passes was negligible, being on the order of 1 percent loss.

The sample attained at 32 is related to the borehole depth by changingthe screen 25 and receptacle 32 each 5 foot of hole, although otherincrements of penetration may be used where deemed desirable. Since thesplitter divides out any desired portion of the returned mud, and sincethe divided portion of the flow stream is identical in composition tothe remainder thereof, the present invention provides formation sampleswhich are more representative of the strata being penetrated than hasheretofore been possible to attain. All of the suspended solids passingthe screen 25 are effectively separated from the liquid in a mannerwhich obviates the necessity of decantation and evaporative treatment ashas heretofore been necessary with prior art devices. By utilizing thepresent invention, each time the screen and receptacle is changed forthe next 5 foot sample, it is now possible to immediately bag theobtained core sample and send it to the geologist. Accordingly, possiblecontamination of the sample is avoided since it is exposed a minimumlength of time to the elements. This also avoids inadvertent interchangeor mix-up of the samples.

This combination of equipment is rugged, inexpensive, and provides theunexpected advantage of enabling relatively liquid free samples to beobtained at outlet 31. The term liquid free formation sample" isintended to mean samples which are saturated in liquid but whichrequires substantially no decantation or evaporation in order to besealed and transported to the geologist.

In carrying out the invention in accordance with the embodimentdisclosed in FIGS. 6-7, the large cuttings are obtained on screen andcombined with the centrifuged solids obtained at 132. The use of asplitter downstream of air separator l 18 is considered optional,depending upon the flow rates involved. While making hole through knownstrata, the valve at 161 can be opened, while valve 162 is closed, so asto flow all of the mud to the mud pit, thereby leaving the pump andcentrifuge inactive until they are needed.

When a mineral bearing strata is encountered, the valve at 161 isclosed, the valve at 162 opened, and circulation through pump 127initiated. Mud now flows into the air separator, through the screen, andinto the reservoir. Make-up water flows from 166, 133 and throughtangental inlet 167 where the side walls of the reservoir are cleaned ofcuttings. The float at 134 maintains a fluid level within the reservoirwhich enables the pump to provide the separator means with a constantflow so as to achieve optimum efficiency of separation.

The liquid outlet from the separator is freely received within the elbow163 of the make-up water storage tank so as to prevent back pressure onthe separator which could adversely affect its operation.

Since the overflow pipe 164 is located below the inlet elbow, thestorage tank will overflow to the mud pit without affecting the liquidflow from the separator. Outlet 166 provides a constant source ofmake-up water to valve 133. Since the solids have been removed from thedrilling mud, the only contaminate which can be contained within themake-up liquid is dissolved minerals. The reuse of this liquid ispreferred to using make-up water which can be obtained from the mud pitfor the reason that insoluble minerals are not recirculated through thesystem. Moreover, soluble minerals will be solublized at a slower rateas the recirculated make-up water dissolves a particular solubleelement.

Where deemed desirable, liquid from outlet 164 can be returned directlyto the borehole so as to achieve a completely closed circulation flowsystem, except for the addition of any make-up water which may berequired for maintaining a proper fluid level within the make-up tank.This modified flow system is especially useful where water is at apremium.

The present invention provides a means of obtaining formation chipsamples which permits both a qualitative as well as a quantitativeanalysis to be achieved since the weight percent of any materialobtained in a formation chip sample can be directly related to the totalamount of material removed from the borehole. This aspect of theinvention is particularly important relative to ores such as copper andmolybdenum, for example, since the economical breaking point ofmolybdenum is at about 0.5 percent, and accordingly 0.1 percent accuracyis very important when making a chemical analysis of the formation chipsample in order to determine the economics of sinking a mine shaft.

The specific splitter means together with the cyclone separator usedherein is indespensible for handling ores which tend to float due totheir surface tension and particle size. Material of this nature wouldotherwise be lost to the mud pit in the absence of the present method.

While a particular pump and cyclone separator have been disclosed hereinfor purposes of illustration, it is pointed out that other pumps andother types of cyclone separators or centrifuge means may be used solong as the inlet pressure and flow rate to the cyclone separator ismaintained within a range which prevents liquid from falling into thereceptacle and prevents carry-over of solids into the discharge.

1 claim:

1. In combination with a borehole forming apparatus having drillingfluid flowing to a drill bit for circulating cuttings to the surface ofthe ground; a formation chip sampling apparatus having:

a reservoir; a pump having an inlet and an outlet; fluid level controlmeans; a source of make-up water; a separator means having an inlet, aliquid outlet, and a formation chip sample outlet;

said pump having the inlet thereof flow connected to said reservoir andthe outlet thereof flow connected to said inlet of said separator means;

said level control means being connected to said source of make-up waterand to said reservoir for maintaining a supply of liquid within saidreservoir;

and means for flow connecting said reservoir to the drilling fluid fromthe borehole bearing the cuttings, whereby:

the separator means removes the cuttings from the drilling fluid toprovide the formation chip sample, while the fluid level controllerenables the pump to provide the separator means with a constant sourceof liquid under pressure.

2. The improvement of claim 1 wherein said means connecting saidreservoir to the drilling fluid includes an air separator and asplitter, said splitter having means for dividing the flow of drillingfluid into a first and second flow path, the first flow path being flowconnected to a mud pit and the second flow path being connected to saidreservoir, so as to reduce the quantity of material which flows to theseparator means.

3. The combination set forth in claim 1, wherein: said means forconnecting said reservoir to the drilling fluid includes a splitter;said splitter having means for dividing the flow of drilling fluid intoa first and second flow path with said second flow path being connectedto the reservoir so as to reduce the quantity of material which flows tothe separator means.

4. The combination set forth in claim 3, and further including a screenmeans interposed between said splitter and said reservoir for removing aportion of the cuttings from said second flow path to thereby reduce theamount of solids which flow to the separator means.

5. The improvement of claim 1 wherein said means connecting saidreservoir to the drilling fluid includes a splitter, said splitterincluding a stator and a rotor, said stator being in the form of anupwardly opening tub, said rotor having a cylinder spaced apart from andcoextensive with said stator, a tubular support member journaled to saidstator, vertically disposed vanes radiating from said tubular supportmember and connected to said cylinder;

a bottom wall interconnecting two adjacent vanes and forming an upwardlyopening catch basin; means forming an aperture through said tubularmember for connecting the catch basin to the interior ofthe tubularmember;

a tubular skirt enclosing the lower extremity of said tubular member forflow conducting fluid caught therein to said reservoir;

and means forming an outlet in said stator for flowing fluid away fromthe stator.

6. The improvement of claim 5 wherein said means connecting saidreservoir to the drilling fluid further includes means forming an airseparator for removing air from the drilling fluid prior to the drillingfluid flowing to the splitter.

7. The improvement of claim 5 and further including a screen meansinterposed between said splitter and said reservoir for removing aportion of the cuttings therefrom.

8. A formation chip sampling apparatus for use in separating formationsamples from drilling fluid, said formation chip sampling apparatuscomprising:

a reservoir having a fluid inlet and a fluid outlet; a cyclone separatormeans having an inlet, a fluid outlet, and a solids outlet; a pump meanshaving an inlet and a discharge;

flow conduit means for flowing drilling fluid and cuttings from aborehole to the reservoir; I a storage tank having a source of make-upliquid therein,

flow conduit means flow connected from said source of make-up liquid tosaid reservoir; valve means for controlling the flow through the lastsaid flow conduit means; liquid level sensing means for determining theliquid level in said reservoir, said sensing means being connected toactuate said valve means for maintaining a supply of liquid in saidreservoir;

flow conduit means by which said pump is flow connected from saidreservoir to said cyclone separator inlet;

flow conduit means by which said liquid outlet of said cyclone is flowconnected to said source of make-up liquid; whereby:

drilling fluid and cuttings flow into said reservoir, to said pump, andto said cyclone separator; while cuttings flow from said solids outletof said cyclone separator; and, liquid flows from the liquid outlet ofsaid cyclone separator to said source of make-up liquid.

9. The formation chip sampling apparatus of claim 8, wherein saidreservoir is a downwardly converging, upwardly opening enclosure means,and said fluid inlet of said reservoir is tangentially disposed withrespect to the interior thereof, whereby the inside peripheral wallsurface of said reservoir is washed by the make-up liquid to therebyprevent deposition of cuttings thereon.

10. The formation chip sampling apparatus of claim 8,

wherein said reservoir is an upwardly opening enclosure means, andfurther including a screen means interposed in the flow path of thefirst recited flow conduit means, to thereby enable a first separationof cuttings to be effected at the reservoir and a second separation tobe effected at said cyclone separator.

11. The formation chip sampling apparatus of claim 8, and furtherincluding an air separator means interposed in the flow path of thefirst recited flow conduit means;

and a splitter means for diverting a fraction of the formation samplesand drilling fluid from said reservoir, to thereby reduce the quantityof fluid flowing through the cyclone separator.

1. In combination with a borehole forming apparatus having drillingfluid flowing to a drill bit for circulating cuttings to the surface ofthe ground; a formation chip sampling apparatus having: a reservoir; apump having an inlet and an outlet; fluid level control means; a sourceof make-up water; a separator means having an inlet, a liquid outlet,and a formation chip sample outlet; said pump having the inlet thereofflow connected to said reservoir and the outlet thereof flow connectedto said inlet of said separator means; said level control means beingconnected to said source of makeup water and to said reservoir formaintaining a supply of liquid within said reservoir; and means for flowconnecting said reservoir to the drilling fluid from the boreholebearing the cuttings, whereby: the separator means removes the cuttingsfrom the drilling fluid to provide the formation chip sample, while thefluid level controller enables the pump to provide the separator meanswith a constant source of liquid under pressure.
 2. The improvement ofclaim 1 wherein said means connecting said reservoir to the drillingfluid includes an air separator and a splitter, said splitter havingmeans for dividing the flow of drilling fluid into a first and secondflow path, the first flow path being flow connected to a mud pit and thesecond flow path being connected to said reservoir, so as to reduce thequantity of material which flows to the separator means.
 3. Thecombination set forth in claim 1, wherein: said means for connectingsaid reservoir to the drilling fluid includes a splitter; said splitterhaving means for dividing the flow of drilling fluid into a first andsecond flow path with said second flow path being connected to thereservoir so as to reduce the quantity of material which flows to theseparator means.
 4. The combination set forth in claim 3, and furtherincluding a screen means interposed between said splitter and saidreservoir for removing a portion of the cuttings from said second flowpaTh to thereby reduce the amount of solids which flow to the separatormeans.
 5. The improvement of claim 1 wherein said means connecting saidreservoir to the drilling fluid includes a splitter, said splitterincluding a stator and a rotor, said stator being in the form of anupwardly opening tub, said rotor having a cylinder spaced apart from andcoextensive with said stator, a tubular support member journaled to saidstator, vertically disposed vanes radiating from said tubular supportmember and connected to said cylinder; a bottom wall interconnecting twoadjacent vanes and forming an upwardly opening catch basin; meansforming an aperture through said tubular member for connecting the catchbasin to the interior of the tubular member; a tubular skirt enclosingthe lower extremity of said tubular member for flow conducting fluidcaught therein to said reservoir; and means forming an outlet in saidstator for flowing fluid away from the stator.
 6. The improvement ofclaim 5 wherein said means connecting said reservoir to the drillingfluid further includes means forming an air separator for removing airfrom the drilling fluid prior to the drilling fluid flowing to thesplitter.
 7. The improvement of claim 5 and further including a screenmeans interposed between said splitter and said reservoir for removing aportion of the cuttings therefrom.
 8. A formation chip samplingapparatus for use in separating formation samples from drilling fluid,said formation chip sampling apparatus comprising: a reservoir having afluid inlet and a fluid outlet; a cyclone separator means having aninlet, a fluid outlet, and a solids outlet; a pump means having an inletand a discharge; flow conduit means for flowing drilling fluid andcuttings from a borehole to the reservoir; a storage tank having asource of make-up liquid therein, flow conduit means flow connected fromsaid source of make-up liquid to said reservoir; valve means forcontrolling the flow through the last said flow conduit means; liquidlevel sensing means for determining the liquid level in said reservoir,said sensing means being connected to actuate said valve means formaintaining a supply of liquid in said reservoir; flow conduit means bywhich said pump is flow connected from said reservoir to said cycloneseparator inlet; flow conduit means by which said liquid outlet of saidcyclone is flow connected to said source of make-up liquid; whereby:drilling fluid and cuttings flow into said reservoir, to said pump, andto said cyclone separator; while cuttings flow from said solids outletof said cyclone separator; and, liquid flows from the liquid outlet ofsaid cyclone separator to said source of make-up liquid.
 9. Theformation chip sampling apparatus of claim 8, wherein said reservoir isa downwardly converging, upwardly opening enclosure means, and saidfluid inlet of said reservoir is tangentially disposed with respect tothe interior thereof, whereby the inside peripheral wall surface of saidreservoir is washed by the make-up liquid to thereby prevent depositionof cuttings thereon.
 10. The formation chip sampling apparatus of claim8, wherein said reservoir is an upwardly opening enclosure means, andfurther including a screen means interposed in the flow path of thefirst recited flow conduit means, to thereby enable a first separationof cuttings to be effected at the reservoir and a second separation tobe effected at said cyclone separator.
 11. The formation chip samplingapparatus of claim 8, and further including an air separator meansinterposed in the flow path of the first recited flow conduit means; anda splitter means for diverting a fraction of the formation samples anddrilling fluid from said reservoir, to thereby reduce the quantity offluid flowing through the cyclone separator.